The present invention refers to a method for longitudinal orientation of hosiery articles such as socks, knee socks or similar for their successive loading on supports for their handling.
Furthermore the invention relates to an apparatus that carries out this method.
In the following description, reference is made to socks, being it clear that the same method can be extended to knee socks and other hosiery articles.
In an automatic production cycle, before that a sock reaches the final packaging, it must follow a path with various working steps.
Usually, at the beginning the sock is picked up automatically or manually from a container and is then subject to intermediate steps that can provide seaming, steaming, up to the final packaging.
For the automatic handling of socks supports are used that are elongated bodies, on which each sock is put, that orient automatically the sock according to a plane of steaming or of seam. For loading socks onto the supports for their handling automatic conveyors are used operated by air currents that drag the socks from a pick up position at the container and load them in turn on a handling support that is present in a loading station.
For loading the sock, the position of the band portion and of the tip portion with respect to the supports must be known. Only in this way the band portion of the sock can be found and manipulated by mechanical means that open it and convey it towards the handling support.
Automatic loading systems exist that pick up socks randomly oriented from a container, that separate them from one another and stretch them by means of air currents. However, such systems do not allow to detect the position of the band portion and of the tip portion with respect to a conveying direction. This needs that an operator controls singularly stretched socks and operates an inversion of the orientation for all those socks for which the band portion and tip portion are arranged in a wrong direction.
It is therefore object of the present invention to provide a method for longitudinal orientation of socks, knee socks or similar that operates in a completely automatic way.
It is, furthermore, an object of the invention to provide an automatic apparatus that carries out this method.
According to the invention, the method for longitudinal orientation provides the steps of:
preliminarily stretching the sock in an orienting duct, whereby the sock is arranged in the duct with its two ends aligned longitudinally;
detecting by means of sensors the position of an end that is either a tip portion or a band portion;
after the detecting step, conveying the sock in the duct in a direction according to which the position is known of the band portion with respect to the tip portion, whereby before the introduction of the sock in a loading duct a step is provided of inversion of the sock if the band portion is not oriented in the chosen direction, or a step of rejection.
Preferably, for conveying the sock an air flow is selectively operated in the duct of orientation, whereby the sock proceeds in the duct in either one or the other direction and is then deviated into a loading duct so that it is conveyed in the loading duct with band portion and tip portion oriented in a predetermined way by the sensor means.
The preliminary stretching step of the sock can be carried out by means of an air flow after preliminary grasping a first end thereof, whereby the second end engages the sensor means.
Preferably, for carrying out the detecting step a mechanical dragging step is provided starting from its second end through the sensors scanning at least a part of the first end thereof.
In a possible embodiment the sensors carry out contemporaneously a scanning step of the sock upstream of the dragging means and downstream of the dragging means, whereby the profiles can be at the same time measured of the first and second end and a comparison between them is made.
Preferably, after the preliminary stretching step the second end of the sock extends between dragging means, the latter pinching the second end and dragging the sock after that the air flow has stopped, the first end being left free and the sensor means scanning the sock in the portion set between the first and second end.
Advantageously, for a correct scanning of the sock, the sock is pressed between the sensor means during the dragging, for stretching any possible folds and improving the scanning conditions.
In a possible embodiment, the sock after the preliminary stretching step moves substantially in a plane, at least a portion of the sock being scanned by the sensors orthogonally to the plane, whereby the sensors recognize the top plan profile of the tip portion or of the band portion.
Alternatively, the sock after the preliminary stretching step moves substantially in a plane and at least a portion of the sock is scanned by the sensors parallel to the plane, whereby the sensors recognize different heights of the side profile of the tip portion or of the band portion.
According to another aspect of the invention, an apparatus for longitudinal orientation of a sock comprises:
a duct of orientation wherein the sock is present with its two ends aligned longitudinally,
sensor means for scanning the profile of the sock at an end and determining whether it is a tip portion or a band portion,
means for creating selectively in the duct of orientation an air flow that drags the sock in a predetermined way and brings it in a loading duct,
means for deviating the sock so that it enters the loading duct with tip portion and band portion oriented in a predetermined way.
Preferably, mechanical dragging means of the sock are also provided along the duct of orientation and through the sensor means, which detect the profile of at least a part of the sock at the passage controlled by the dragging means.
The dragging means can comprise at least two dragging rollers that pinch the sock and convey it so that at least a portion thereof passes through the sensor means.
In a possible embodiment, the sensor means are grouped as first sensors upstream of the dragging means and seconds sensors downstream of the dragging means, whereby the profiles can be at the same time measured of the first and second end and a comparison between them is made.
Preferably, the sensor means comprise a head that pushes the sock against a counter-surface belonging to the duct, whereby the sock is dragged between the head and the counter-surface for stretching any possible folds and to allow a correct detecting step of its profile.
In a preferred embodiment, means are provided for stretching the sock in the duct comprising:
means for grasping a first end thereof leaving the second end free,
means for creating an air flow from the first to the second end;
means for blocking the dragging means against the second end stretched by the air flow, the dragging means dragging the sock after that the air flow has stopped, the first end being left free at the sensor means and at least a part of the sock crossing the sensor means.
Preferably, in the duct of orientation two grids are provided movable between a open position and a closed position, at each grid grasping means being provided, the sensor means and the dragging means being arranged between said two grids.
The sensor means comprise advantageously an array of sensors with a density that allows a sufficient definition of the contour of the end of the sock. They can be chosen among: optical, mechanical, pneumatics, electrical sensors.